John Caron wrote:
It seems like there are 2 use cases people have in mind:
1. A data provider is using this Convention to write out data.
Presumably the provider is working hard to put quality metadata into
their files. I'd really like to encourage (require?) them to put in
time, z, x, and y geolocation information. Is there really a case
where that information is not available at the raw data writing?
2. Middleware software is using this Convention as an exchange format,
ie rewriting original data into this format. Here, its quite possible
that the z coordinate in particular is missing.
The work that our group does falls into this category. I don't know of
any point observation data we have that either does not have the
z-coordinate specified or can be
known from associated documentation. The hurricane track data that was
previously mentioned, for example, does not explicitly include the
z-coordinate, but the format
documentation states that the wind and pressure are valid at the
surface, so the z-coordinate can be specified during the translation
from native format to CF-compliant
netCDF. My opinion is that option 4 is the way to go, with the ability
to specify "unknown" if z is really not known, but at least data users
will know that it wasn't unintentionally
omitted, and data providers and translators will maybe be prodded to
work a little harder to include it.
UCAR/NCAR/CISL/Data Support Section
Phone: (303) 497-1825